By NIELS LESNIEWSKI and BRIDGET BOWMANCQ Roll Call

Senators from both parties want to know if President Donald Trump has the gumption to stand up to Syrian leader Bashar al-Assad — and by extension Russian President Vladimir Putin.

That question was raised after Assad’s forces reportedly carried out a deadly gas attack earlier this week that left dozens dead.

Trump again put most of the blame for the situation in Syria on former President Barack Obama, saying his decision in August 2013 against using U.S. military force there “set us back a long ways” in Syria and across the globe. He later said Obama left him a “mess” of a global security and threat picture, and Trump, in his characteristically brash way, vowed to clean it up — though he mentioned not one specific plan for doing so.

“This is the biggest test yet of the Trump presidency,” Sen. Lindsey Graham said in a statement. “The President has an opportunity to punish Assad in a way that President Obama never would.

Graham described the incident as “the moment for President Trump to prove to everyone that when it comes to foreign policy and standing up to dictators, he is not President Obama.”

The South Carolina Republican and others on Capitol Hill said they have no doubts that Assad’s regime used chemical weapons against children as recently as Tuesday, even as Russia said the Syrian government was not at fault.

“Vladimir Putin is a war criminal who is assisting another war criminal in killing his own people, in gassing innocents,” said Sen. Marco Rubio, a member of the Foreign relations committee. “And for me, a statement is not enough … There needs to be a level of outrage. It needs to become a priority.”

The Florida Republican joined Sen. Benjamin L. Cardin, D-Md., at a Wednesday press conference calling on the Trump administration to set a clear policy that Assad must go.

“We need action,” said Cardin, the top Democrat on Foreign Relations. “To me it starts with a clear U.S. policy that President Assad has no legitimacy as the leader of Syria and no future as the leader of Syria.”

Cardin also called for additional sanctions against those supplying the Assad regime, and said the U.S. should work with its global partners to indict the president on war crimes.

Trump said Wednesday that Obama’s failure to enforce his announced “red line” against Assad’s use of chemical weapons was “not one of our better days as a country.”

But the still-new commander in chief, wearing his signature red tie on a warm spring day in the White House Rose Garden, told reporters “I now have that responsibility” to respond.

As he has since the campaign, Trump vowed that he will not telegraph any military response.

On Tuesday, White House Press Secretary Sean Spicer said Assad should step down.

But Trump’s top foreign policy officials including U.N. Ambassador Nikki Haley and Secretary of State Rex Tillerson had recently indicating that ousting Assad was not a top priority, and that the focus was on defeating the Islamic State terror group, also known as ISIS.

Graham and Senate Armed Services Chairman John McCain met Tuesday afternoon with Tillerson.

McCain, an Arizona Republican, said Tillerson, “realizes that we’ve got to take action against these elements that are committing war crimes as we speak.”

“This is a new administration. This is a crisis, let’s let them sort it out,” McCain said Wednesday.

Rubio told a Tampa radio show Wednesday morning that it was not a coincidence the chemical attack followed Tillerson’s statements. He elaborated at Wednesday’s press conference with Cardin that he did not believe permitting an attack was Tillerson’s intention.

But Rubio said the administration was sending a signal to Assad that although the U.S. condemns his actions, the priority is combating ISIS.

“I think that is, in my view, something that would encourage [Assad] to do something like what we’ve just seen,” Rubio said, referring to Tillerson’s statement.

Rubio and Cardin argued that combating ISIS and ousting Assad are not mutually exclusive priorities. Instead, Rubio argued, attacks by Assad can spur Syrians to join extremist groups to fight the regime.

Trump said Wednesday the Syrian chemical attack “crosses many lines” for him, but replied to several questions that he will not signal any U.S. response beforehand.

Tillerson said in his confirmation hearing, “The clear priority is to defeat ISIS. We defeat ISIS we at least create some level of stability in Syria which then lets us deal with the next priority of what is going to be the exit of Bashar Assad.”

Asked Wednesday if Rubio regretted voting for Tillerson to become the Secretary of State, Rubio said, “My concerns from those hearings remain, but I’m not prepared to go as far as your question.”

Though the Trump administration has now said Assad should not remain the leader of Syria, Trump’s statement after the attack placed most of the blame for the attack on President Barack Obama, saying the attack was “a consequence of the past administration’s weakness and irresolution.”

Senate Minority Leader Charles E. Schumer criticized that response.

“Instead of action there’s just blame,” the New York Democrat told reporters. “Blame doesn’t solve the problem.”

Both Cardin and Rubio said they must move forward from the previous presidency.

Republicans have particularly criticized Obama for not taking action to enforce his so-called “red line” with respect to Assad, pushing Trump to pursue a different course.

“Now President Trump is the president, not President Obama, and I would counsel him that the policy needs to be what it was stated under the Obama administration, but never actually pursued. Bashar al-Assad must ultimately go,” Sen. Tom Cotton, R-Ark., said on MSNBC. “It may not be tomorrow, it may not be next week, ISIS may be our more immediate threat from Syria, but we cannot be safe as long as the Assad-Iran-Russia axis is in charge in Syria.”

“We’ve seen this movie before. Barack Obama is directly responsible for this,” McCain told reporters. “Saying nothing is bad. Saying you’re going to do something and doing nothing is ten times worse.”

John T. Bennett contributed to this report.